Preface 



Barely four years ago, an effort was made to summarize the existing 

 knowledge of the nature and physiology of the actinomycetes in a book 

 entitled "The Actinomycetes." No attempt was made to include in that 

 volume any detailed system of classification or species characterization of 

 these organisms, since it was felt that Bergey's Manual was quite sufficient 

 for that purpose. Nor was any attempt made to characterize in detail the 

 antibiotics produced by actinomycetes, since the available information was 

 rather limited at that time. 



The rapid progress made during the last few years in the screening of 

 actinomycetes, especially of species belonging to the genus Streptomyces, 

 for their ability to produce antibiotics, the use of many of these antibiotics 

 for chemotherapeutic purposes, and the addition of numerous descriptions 

 of new species of actinomycetes necessitate a more detailed presentation of 

 the systematic position and identification of these organisms and of the 

 antibiotics produced by them. In describing these new organisms, many 

 investigators have been unable to identify their newly isolated cultures 

 with those described in the last edition of Bergey's Manual, with the result 

 that they preferred to give their cultures new names, often without regard 

 to the established types. These new descriptions are found in various jour- 

 nals and even in patents. This guide has been prepared for the primary 

 purpose of making this information available to workers in this field. Those 

 species which have been insufficiently described or which appear to be 

 synonyms are not listed in the guide, but will be found in the new edition 

 of Bergey's Manual, now in the process of preparation. 



In the preparation of this guide, advantage has been taken of progress 

 made in the classification of the actinomycetes during the last 30 years, 

 thanks largely to the work of Orskov, Jensen, Waksman and Henrici, 

 Erikson, and Krassilnikov. Much, however, still remains to be done, espe- 

 cially on the physiology and biochemistry of actinomycetes. This is true 

 particularly of one group of metabolic products, namely, the antibiotics. 

 Because these substances have become so vitally important, an effort has 

 been made to fist all the antibiotics so far isolated, either in crude or in 

 pure form, and to give their salient properties and uses. 



This guide has been prepared with the primary purpose of facilitating 

 the work of the student of antibiotics produced by actinomycetes and to 

 help him in the identification of the organisms producing these antibiotics, 

 as well as of the antibiotics themselves. 



The authors want to express their sincere appreciation to Mrs. Her- 

 minie B. Kitchen for her editorial assistance in the preparation of this 

 volume and for her painstaking help in its proofreading. 



